Search results
Results from the WOW.Com Content Network
Smog, or smoke fog, is a type of intense air pollution. The word "smog" was coined in the early 20th century, and is a portmanteau of the words smoke and fog [ 1 ] to refer to smoky fog due to its opacity, and odor. [ 2 ] The word was then intended to refer to what was sometimes known as pea soup fog, a familiar and serious problem in London ...
The geological history of the Earth follows the major geological events in Earth's past based on the geological time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk-shaped mass of dust and gas left ...
e. Air pollution is the contamination of air due to the presence of substances called pollutants in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. [ 1 ] It is also the contamination of the indoor or outdoor environment either by chemical, physical, or biological ...
The geologic time scale, proportionally represented as a log-spiral with some major events in Earth's history. A megaannus (Ma) represents one million (10 6) years. The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses ...
Ground-level ozone. Seasonal average vertical columns of tropospheric ozone in Dobson units over the period 1979 to 2000. In June to August, photochemical ozone production causes very high concentrations over the East Coast of the US and China. Ground-level ozone (O3), also known as surface-level ozone and tropospheric ozone, is a trace gas in ...
v. t. e. The history of environmental pollution traces human-dominated ecological systems from the earliest civilizations to the present day. [ 1 ] This history is characterized by the increased regional success of a particular society, followed by crises that were either resolved, producing sustainability, or not, leading to decline. [ 2 ][ 3 ...
The first eon in Earth's history, the Hadean, begins with the Earth's formation and is followed by the Archean eon at 3.8 Ga. [2]: 145 The oldest rocks found on Earth date to about 4.0 Ga, and the oldest detrital zircon crystals in rocks to about 4.4 Ga, [34] [35] [36] soon after the formation of the Earth's crust and the Earth
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...